Small group number 237 of order 64
G is the group 64gp237
The Hall-Senior number of this group is 168.
G has 4 minimal generators, rank 3 and exponent 4.
The centre has rank 2.
There are 2 conjugacy classes of maximal
elementary abelian subgroups. Their ranks are:
3, 3.
This cohomology ring calculation is complete.
Ring structure
| Completion information
| Koszul information
| Restriction information
| Poincaré series
The cohomology ring has 7 generators:
- y1 in degree 1, a nilpotent element
- y2 in degree 1, a nilpotent element
- y3 in degree 1
- y4 in degree 1
- v1 in degree 4
- v2 in degree 4, a regular element
- v3 in degree 4, a regular element
There are 6 minimal relations:
- y3.y4 =
y2.y4
+ y12
- y1.y4 =
y1.y3
+ y22
+ y12
- y22.y4 =
y22.y3
- y1.y22 =
y12.y2
+ y13
- y1.v1 =
y13.y2.y3
- v12 =
y44.v1
+ y34.v1
+ y44.v2
+ y34.v2
+ y13.y2.v2
A minimal Gröbner basis for the relations ideal
consists of this minimal generating set, together with the
following redundant relations:
- y1.y32 =
y22.y3
+ y1.y2.y3
+ y12.y3
+ y23
+ y12.y2
+ y13
- y22.y32 =
y23.y3
+ y13.y2
- y24 =
y13.y2
- y14 =
0
- y22.v1 =
0
This cohomology ring was obtained from a calculation
out to degree 12. The cohomology ring approximation
is stable from degree 8 onwards, and
Benson's tests detect stability from degree 8
onwards.
This cohomology ring has dimension 3 and depth 2.
Here is a homogeneous system of parameters:
- h1 =
v2
in degree 4
- h2 =
v3
in degree 4
- h3 =
y42
+ y32
in degree 2
The first
2 terms h1, h2 form
a regular sequence of maximum length.
The first
2 terms h1, h2 form
a complete Duflot regular sequence.
That is, their restrictions to the greatest central elementary abelian
subgroup form a regular sequence of maximal length.
Data for Benson's test:
-
Raw filter degree type:
-1, -1, 5, 7.
-
Filter degree type:
-1, -2, -3, -3.
-
α = 0
-
The system of parameters is very strongly quasi-regular.
-
The regularity conjecture is satisfied.
A basis for R/(h1, h2, h3) is as follows.
-
1
in degree 0
-
y4
in degree 1
-
y3
in degree 1
-
y2
in degree 1
-
y1
in degree 1
-
y32
in degree 2
-
y2.y4
in degree 2
-
y2.y3
in degree 2
-
y1.y3
in degree 2
-
y22
in degree 2
-
y1.y2
in degree 2
-
y12
in degree 2
-
y2.y32
in degree 3
-
y22.y3
in degree 3
-
y1.y2.y3
in degree 3
-
y12.y3
in degree 3
-
y23
in degree 3
-
y13
in degree 3
-
v
in degree 4
-
y23.y3
in degree 4
-
y13.y3
in degree 4
-
y4.v
in degree 5
-
y3.v
in degree 5
-
y2.v
in degree 5
-
y32.v
in degree 6
-
y2.y4.v
in degree 6
-
y2.y3.v
in degree 6
-
y2.y32.v
in degree 7
A basis for AnnR/(h1, h2)(h3) is as follows.
-
y22
in degree 2
-
y1.y2
+ y12
in degree 2
-
y22.y3
in degree 3
-
y1.y2.y3
+ y12.y3
in degree 3
-
y23
in degree 3
-
y13
+ y1.h
in degree 3
-
y1.h
in degree 3
-
y23.y3
in degree 4
-
y13.y3
+ y1.y3.h
in degree 4
-
y1.y3.h
in degree 4
-
y12.h
in degree 4
-
y12.y3.h
in degree 5